The present invention relates to an improvement in a closed-type electromagnetic compressor, and more particularly relates to improved collimation and lubrication mechanisms in a closed-type (i.e., sealed) compressor preferably used for cooling systems in which both driving and pumping parts reciprocate in the axial direction of the compressor for compressive pumping action.
A closed-type compressor provided with an electromagnetic drive is already known in the art. In the construction of the compressor of this type, at least one stator core is connected via a half-wave rectifier circuit to a given AC source and a magnetic armature is allowed to reciprocate in the axial direction of the compressor across, i.e., substantially at a right angle to the line of magnetic induction generated by the stator core. The armature is integrally coupled with a piston which carries out the pumping action by its reciprocation in the piston chamber. When a pair of axially spaced stator cores are provided, electromagnetic attractions generated by alternate excitation of the two stator cores and acting on the armature cause reciprocation of the piston. Whereas, when only one set of stator core is used, movement of the piston in one direction is caused by the magnetic attraction acting on the armature and movement of the piston in the other direction is caused by a separate urging mechanism acting mechanically on the piston. One typical example of such an urging mechanism is given in the form of a return spring.
However, it is well known that conventional compressors of the above-described type have never been welcomed in the actual field of industry. Major causes for this poor acceptance of the conventional machines in the actual field of industry are thought to be as follows.
In the case of compressors of the rotary drive type, one end of the crank shaft of the rotary electric motor is immersed within lubrication oil so that the oil is supplied to the shaft bearing parts as the shaft rotates. In another example, a screw pump type oil supply system is used for lubrication.
In contrast to this, the compressor of the above-described reciprocal drive type contains no rotary shaft in its construction and, therefore, the above-mentioned lubrication system employed in the rotary drive type compressors cannot be utilized for lubrication of the reciprocal drive type compressors. This requires provision of a separate oil supply pump in the construction of the reciprocal drive type compressors entailing complicated construction, troublesome maintenance and escalated manufacturing costs.
Further, in the pumping mechanism of the reciprocal drive type compressors, reciprocation of the piston with the armature plays the most important decisive role. So, when the collimations of the armature with the stator core and of the piston with the bearing part are not in order, biased attraction on the armature and/or biased load on the piston has an undesirable influence on the life of the piston and its related parts. In order to obviate such problems, precise collimation must be established between the above-mentioned elements, which in general calls for complicated, time-consuming and highly skilled work in assembling the compressors.